Anisotropic cell growth-regulated surface micropatterns in flower petals

Flower petals have not only diverse macroscopic morphologies but are rich in microscopic surface patterns, which are crucial to their biological functions. Both experimental measurements and theoretical analysis are conducted to reveal the physical mechanisms underlying the formation of minute wrinkles on flower petals. Three representative flowers, daisy, kalanchoe blossfeldiana, and Eustoma grandiflorurn, are investigated as examples. A surface wrinkling model, incorporating the measured mechanical properties and growth ratio, is used to elucidate the difference in their surface morphologies. The mismatch between the anisotropic epidermal cell growth and the isotropic secretion of surficial wax is found to dictate the surface patterns.

Improvements of dielectric properties and energy storage performances in BaTiO_(3)/PVDF nanocomposites by employing a thermal treatment process

The influence of thermal treatment on the dielectric properties and energy storage performances of a classical dielectric nanocomposite system(barium titanate/polyvinylidene fluoride PVDF)was discussed systematically.The results demonstrated that the permittivity of thermal treated nanocomposites increased and dielectric loss decreased compared with the untreated system.In addition,the energy density was also greatly improved due to the inclined residual polarization.For example,the energy density of the treated nanocomposite with 50 vol.%nanofillers was 3.14 times higher than the untreated nanocomposite at 50 MV/m.Moreover,the charge–discharge efficiency was also promoted from 6.36%to 56.89%.According to the viewpoint of microstructure,the improvement of the dielectric and energy storage properties would be ascribed to the suppression on void defects in the interphase of dielectric nanocomposite by employing the thermal treatment process.Finally,thermal treatment turns out to be a simple and an effective method to improve the dielectric performances and energy storage properties in the dielectric nanocomposites.

Properties of Ahlfors constant in Ahlfors covering surface theory

This paper is a subsequent work of[Invent.Math.,2013,191:197-253].The second fundamental theorem in Ahlfors covering surface theory is that,for each set E_(q)of q(≥3)distinct points in the extended complex plane C,there is a minimal positive constant H_(0)(E_(q))(called Ahlfors constant with respect to E_(q)),such that the inequality(q-2)A(Σ)-4π#(f^(-1)(E_(q))∩U)≤H_(0)(E_(q))L(ЭΣ)holds for any simply-connected surfaceΣ=(f,U),where A(Σ)is the area ofΣ,L(ЭΣ)is the perimeter ofΣ,and#denotes the cardinality.It is difficult to compute H_(0)(E_(q))explicitly for general set E_(q),and only a few properties of H_(0)(E_(q))are known.The goals of this paper are to prove the continuity and differentiability of H_(0)(E_(q)),to estimate H_(0)(E_(q)),and to discuss the minimum of H_(0)(E_(q))for fixed q.